SQL AFTER Vs BEFORE TRIGGER Statement
MySQL is a popular DBMS that enables users to easily retrieve and manage data in relational databases.
It keeps data in a tabular format.
Structured Query Language allows the user to perform a variety of operations on data (SQL). Trigger, on the other hand, is a store programme that executes when an event occurs.
The response to the trigger is determined by the type of trigger.
The primary distinction between Before and After triggers in MySQL is that Before trigger performs an action before a specific operation on the table.
whereas After trigger performs an action after a specific operation on the table.
SQL AFTER TRIGGER Statement
The AFTER trigger is a sort of trigger that executes automatically after a specific operation on the table.
AFTER triggers execute the trigger action following the execution of the triggering statement.
The AFTER trigger is used to update the accounts table balance.
SQL BEFORE TRIGGER Statement
BEFORE triggers executes the trigger action prior to the execution of the triggering statement. This type of trigger is frequently used in the following circumstances:
When the trigger action is performed, it determines whether the triggering statement should be allowed to finish.
By using a BEFORE trigger for this purpose, you can avoid unnecessary processing of the triggering statement and its eventual rollback if an exception is raised in the trigger action.
In a banking application, using a before trigger allows you to double-check the values before deleting them.
SQL Difference Between AFTER And BEFORE TRIGGER Statement
Here,we discuss the contrasts in trigger statement of after vs before:-
|BEFORE TRIGGER||AFTER TRIGGER|
|A type of trigger that executes automatically before a specific table operation occurs.||A type of trigger that executes automatically when a specific operation on the table occurs.|
|Before triggers are typically used to perform validation before accepting data into the table and to check the values before deleting them from the table.||Used to update data in a table as a result of a change.|
|BEFORE trigger-The trigger action is executed before the triggering statement is executed.||AFTER triggers-AFTER Triggers execute the trigger action following the execution of the triggering statement.|
|BEFORE row trigger||row trigger AFTER|
|If the trigger restriction was not violated, the trigger action is executed before modifying each row affected by the triggering statement and before checking appropriate integrity constraints.||If the trigger restriction was not violated, the trigger action is run for the
|BEFORE row triggers can be used to modify a row before it is written to disc.||Use AFTER row triggers to obtain the row ID and perform operations on it.|
|A BEFORE UPDATE trigger, for example, will fire before the update operation is executed.||The AFTER UPDATE trigger will be triggered following the update statement.|
|BEFORE row triggers outperform AFTER row triggers by a small margin.||BEFORE row triggers are more efficient than AFTER row triggers.|
|PRIOR to row triggers, the data blocks must only be read once for both the triggering statement and the trigger.||AFTER row triggers, affected data blocks must be read (logically, not physically) twice: once for the trigger and once for the triggering statement.|